The present invention relates to a band combining filter and a signal transmitter including such a filter. More particularly, but not exclusively, the present invention relates to a band combining filter comprising a plurality of directional filters connected together in a cascade.
There is an interesting demand to combine different types of communications systems on to a common antenna by subdividing a communication band by frequency allocation. There are several known techniques by which this may be accomplished however the need for a high power and high linearity makes known systems complex and expensive.
The band combining filter according to the invention seeks to overcome this problem.